The invention provides lipophilic conjugates comprising a short isolated peptide coupled to a hydrophobic moiety, the peptide comprising a sequence derived from the HIV-1 gp41 N-terminal heptad repeat domain, said peptide after conjugation to the hydrophobic moiety possesses anti-fusogenic activity higher than prior to conjugation. The lipophilic conjugates are suitable for treatment of infections caused by human and non-human retroviruses, especially HIV.